In feeding cattle, especially dairy cattle, feeding of silage and haylage is a common practice, but until this time, there has been no satisfactory apparatus for pneumtically conveying such silage and haylage for substantial distances. It will be recognized that silage is usually considered to be corn, harvested early while the stems, leaves, and ears are still green and soft, and the corn, harvested in this way, is chopped and blown into a silo. Haylage is somewhat generally similar, but is hay which has been harvested while it is still relatively green and high moisture, and the hay is chopped into particles and then blown into the silo. Of course, when the silage and haylage is removed from the silo, it must be conveyed to the cattle for feeding, either in stanchions, feed bunks, or similar type feeding devices. Various types of carts, auger conveyors, and belt conveyors have been used in conveying silage and haylage.
Of course, pneumatic conveyors have been previously used for conveying various granular and powder type materials, all of which have a relatively low moisture content at the time they are being used or conveyed. However, silage and haylage is generally relatively wet as it is taken from a silo and then used as cattle feed. For instance, haylage and silage may be as wet as 70% moisture, and often times the haylage and silage is well in excess of 40% moisture. In some instances, the silage may be less than 40% moisture, but it is unusual that such haylage have the low moisture content comparable to bailed hay, which may be in the range of 20% moisture.
Corn silage is generally made up of fairly uniform size particles; but on the other hand, haylage is not uniform like corn silage, and the stems and particles vary rather widely in size. For instance, in haylage, it is not at all uncommon that the stems and particles vary from one-fourth of an inch to one inch in length.
In addition to the other particles in corn silage, often times there is shelled corn mixed in with the silage with a rather high moisture content of 23% or more.
The high moisture content, variable moisture content, and the irregular particle size of haylage, and the high moisture content of silage, makes these materials difficult to handle without stopping in the flow lines in a pneumatic system.